A photovoltaic system (informally, PV system) is an arrangement of components designed to supply usable electric power for a variety of purposes, using the sun (or, less commonly, other light sources) as the power source. PV systems may be built in various configurations: off-grid without battery (array-direct); off-grid with battery storage for DC-only appliances; off-grid with battery storage for AC and DC appliances; grid-tie without battery; and grid-tie with battery storage.
A photovoltaic array (also called a solar array) consists of multiple photovoltaic modules, casually referred to as solar panels, to convert solar radiation (sunlight) into usable direct current (DC) electricity. A photovoltaic system for residential, commercial, or industrial energy supply normally contains an array of photovoltaic (PV) modules, one or more DC to alternating current (AC) power converters (also known as inverters), a racking system that supports the solar modules, electrical wiring and interconnections, and mounting for other components. Optionally, a photovoltaic system may include any or all of the following: a revenue-grade meter, a maximum power point tracker (MPPT), a battery system and charger, a global positioning system (GPS) solar tracker, energy management software, solar concentrators, solar irradiance sensors, an anemometer, or task-specific accessories designed to meet specialized requirements for a system owner. The number of modules in the system and the modules' rated capacity determines the total DC watts capable of being generated by the solar array; however, the inverter ultimately governs the amount of AC watts that can be distributed for consumption.
Conventionally, solar PV panels are often installed on roofs and are typically set tilted and arranged in spaced-apart rows. For flat roofs, there is more flexibility for how to place the arrays. There have been many investigations into the optimal tilt for solar PV system to maximize the energy production (i.e., maximize the conversion of solar radiation (sunlight) into usable direct current (DC) electricity). Many of these analyses consider solar energy production assuming that a southern azimuth (in the northern hemisphere) is optimal for energy production. While the south-orientated rule-of-thumb might be best for completely clear skies, non-uniform, temporal meteorological conditions, such as fog or clouds, environmental conditions, such as smog, and geographic features, such as mountains, can block solar radiation and reduce solar panel output at different times of the day and change the optimal orientation of the panels. Additionally, solar PV power output is a function of panel temperature and/or panel materials, so dry bulb temperature fluctuations and wind speed (because of convective heating or cooling) can also alter PV electricity production profiles.
Another consideration for optimal PV orientation is the value of the electricity generated. Because solar energy production does not always precisely align with maximum electricity grid load or price, even placements that might be non-optimal from an energy production basis might be optimal on an economic or peak power production basis. For example, one analysis used day-ahead market electricity prices to determine optimal solar PV orientations in California. The conclusion of such an analysis was that the market electricity prices shifted the optimal orientation of some arrays west of south.
While there have been some analysis in determining the optimal tilt and azimuth angles as well as determining the optimal PV orientation based on the value of the electricity generated, there has been no analysis considering the production of AC electricity (after panel, inverter and other derate losses) as the metric for optimal placement. Furthermore, such analyses were limited to a local geographic area without considering multiple economic inputs. Additionally, such analyses did not consider the value of energy production from the perspective of various users (e.g., residential customers, utility companies, businesses), where the “value” may correspond to an economic value or a non-economic value (e.g., reduction in carbon dioxide).